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Plug-in hybrid electric vehicles release almost five times more planet-heating pollution than official data indicate, as per a recent analysis.

Growing Gap In Lab and Real-World CO2 Output

Statistics shows that PHEVs release only 19% less CO₂ than conventional gas and diesel vehicles, based on research carried out by a non-profit organization. That contrasts sharply with laboratory tests, which suggested a 75% reduction in emissions.

Analysts examined information from onboard fuel consumption meters of 800,000 vehicles registered in Europe from 2021 and 2023. They found that real-world CO₂ emissions from PHEVs in 2023 were nearly five times higher than official figures, up from 3.5 times in 2021.

“Real-world CO2 output are rising, while lab-reported figures are decreasing,” stated a lead analyst participating in the study. “This gap is widening and creates a serious issue. As a result, PHEVs pollute nearly as much as petrol vehicles.”

Key Reasons Driving the Emissions Gap

Researchers attributed the majority of the difference to overestimates of the “utility factor” – the ratio of kilometers driven in electric mode compared to overall mileage. They found that only 27% of driving was done in EV mode, whereas lab estimates assumed 84%.

Additionally, when operating in EV mode, emission amounts were well above lab projections. That occurred because EV motors were insufficiently powerful sufficient to operate alone, resulting to combustion motors burning gasoline for nearly a third of the distance completed in EV mode.

Regulatory and Financial Consequences

According to estimates, the underestimation of PHEV CO2 output allowed four major carmaker groups to escape over €5bn in penalties between 2021 and 2023, by falsely easing compliance with EU fleet-average CO₂ targets.

Additionally, owners of PHEVs could pay about €500 extra per year in operating expenses than would be assumed under lab conditions.

“The bold claims that automakers like to make about their PHEV cars are clearly way off the mark,” commented a automotive expert. “Buyers are being misled into believing that by buying a PHEV, they are helping the planet and cutting costs. In reality, PHEVs are little improved than regular petrol and diesel vehicles in terms of energy use, CO₂ production, and operating costs.”

Political Debate and Automotive Pressure

Hybrid cars have lately been drawn back into political discussions as carmakers have pressed the European Union to relax CO₂ targets. A planned ban on sales of new combustion engine vehicles in 2035 has faced intense lobbying from the automotive industry and resistance from EU countries with large automotive industries.

Some high-level politicians have suggested plug-in hybrids as a possible “compromise” solution to introduce in the legislation.

An independent energy policy specialist, who was not involved with the research, described the report a “highly valuable addition” after years in which parts of the automotive sector argued there was insufficient data to properly evaluate actual emissions.

“The results demonstrate, beyond any doubt, that the gap between official and real-world PHEV fuel consumption and CO₂ emissions is much, much larger than for gasoline or conventional cars,” they said. “Any regulatory adjustments regarding PHEVs should be made with extreme caution and in the light of this evidence.”